Place meat in a large stew pot and cover with water. Boil for 2-3 hours until tender when pierced with a fork. Remove from the pot (saving the water), place on platter, and cover with foil to retain heat while vegetables cook. Place potatoes, carrots, onions, and turnip in the pot and boil 30 minutes. Add cabbage and boil for another 15 minutes. Mix together mustard, flour, salt and one cup evaporated milk. Put the rest of the milk and sugar in the top of a double boiler and turn heat on. Add mustard mixture slowly while whisking. Add egg yolks slowly continuing to whisk. Heat to thicken. When thick, add heated vinegar and remove from heat. Slice the beef in diagonal slices across the grain. Drain vegetables and arrange all on a platter. Serve with Irish soda bread and a pitcher of warm mustard sauce. This recipe will make about six servings.